This invention relates to information display systems, and particularly to ambient light powered information display systems suitable for use with shelving of the kind used in supermarkets, stores, and the like.
Information display systems are commonly used in applications where products for sale are placed on shelves. These systems typically display information, such as the name of the product, price, unit price, and product identification codes, on rails attached to the shelves, with the information placed directly above or below the product. These systems are used to provide the information to customers and to facilitate product ordering and inventory control.
Some of these systems use electronic display modules which require a power source to power the display module. A controller may be used to communicate with the display modules to change and confirm the display information.
In one such system, multiple conductors are used both carry to power and to communicate with the display modules. However, the wiring necessary to implement this system is complex and expensive. Further, once installed, this system is difficult to change when the gondola containing the shelving must be moved, as often occurs for replacement, remodelling or marketing reasons.
In another system, radio frequency (RF) signals are used to communicate with individual electronic displays to change the information displayed. Each display module is provided with an RF transmitter and receiver to communicate with the controller. These systems are costly because the RF transceivers are costly. Another problem with such systems is that the RF transceivers practical for such systems have limited range and require that the receiver be located nearby. In one such system, for example, a receiver or remote antenna must be located above each gondola. The multiple RF receivers greatly increase the cost of such systems. Moreover, the use of RF bands is controlled by government regulations. Because the regulations vary from country to country, the RF systems are not easily xe2x80x9cportablexe2x80x9d; i.e., they may need to be customized for each country to meet its regulations.
Another type of system uses an infra-red (IR) communication system to control display modules. Each display module is self powered by a photovoltaic cell and is provided with an IR transmitter and receiver. This system is able to use photovoltaic power (sometimes called xe2x80x9csolar powerxe2x80x9d) because IR systems require less power to operate than RF systems. However, the IR transmitter in each display module must be relatively weak to reduce power consumption, and thus the controller must have an IR receiver placed within short range and preferably within line of sight of each display module. Even so, the display module must also limit its transmissions to restrict its power consumption.
Although an IR system uses less power than an RF system, a large solar cell is needed to power each display, which in turn makes the display module relatively large. A large module may not be usable with smaller products and closely spaced shelf facings and may detract from the appearance of the products placed on the shelves. Of course, the larger photovoltaic cell tends to increase the cost of the display module.
An assumption underlying the prior art systems in general is that a single transmission spectrum (i.e., RF or IR) should be used to communicate in both directions with the display modules.
In accordance with this invention, an information display system comprises a controller, a ceiling node a rail, an end cap, and a solar powered display module. The display module stores and displays information. The controller, among other functions, communicates with the display module, via the ceiling node, to update and verify the information in the display module. The ceiling node communicates with the display module, via the end cap through an IR downlink and an RF uplink. The IR transmitter transmits a relatively high power signal to ensure good reception with a high sensitivity but low power IR receiver. The RF transmitter is a relatively low power transmitter which may be, for example, similar to those commonly used in remote control devices which are not tightly controlled by the RF communication regulations in most countries. By combining RF and IR communication systems in the information display system, not only is communication between the controller and the module accurate and robust, but also the module""s size and power consumption are reduced to make a solar-powered information display system practical.
For supermarket applications, one embodiment of the present invention comprises a network computer, a controller, a plurality of ceiling nodes, a plurality of self-powered end caps mounted to individual shelves or gondolas, and a plurality of solar powered display modules wired to each end cap via a wired rail. Each display module displays price information for a corresponding product and provides excess solar power to charge an energy storage device in the end cap to which the display module is coupled. This permits the sharing of power among the display modules that are coupled to a particular end cap and eliminates any additional wiring needed to power the end cap.
The network computer sends price information to the controller to broadcast to the individual display modules via the ceiling nodes and end caps, thus allowing the user to quickly and automatically update prices for its products. The display module includes an optical port, which allows Universal Product Code (UPC) information to be entered directly into a display module by a portable UPC reader device to easily and accurately reprogram the display module for a different product. The RF uplink allows the display module to communicate with the controller and to verify the programmed UPC information.